1. Field of the Invention
This invention relates in general to door edge guards mounted on the trailing edges of automobile doors and to methods of manufacturing such door edge guards. In particular, the invention relates to insulated metal door edge guards having a color to match the color of the automobile door to which the door edge guard is to be attached.
2. Description of the Prior Art
Door edge guards are mounted on the trailing edges of automobile doors to protect the edges of the doors and to protect objects that are struck by the door edge. For example, in a crowded parking lot the door edge may strike the side of an adjacent automobile. Without door edge guards, the door edges may be chipped and subsequently rust.
Both metal and non-metal door edge guards are manufactured. Non-metal door edge guards are made of various plastics, such as polyvinylchloride (PVC). Metal door edge guards are generally made of stainless steel or aluminum. If the metal of the guard is different from the metal or the door, usually carbon steel, then the two metals must be insulated to prevent electrochemical action between the two metals from causing galvanic corrosion. Insulating materials are generally plastics, such as PVC.
In many prior art door edge guards aluminum is used because the galvanic corrosion does not produce red rust. However, stainless steel has more resilience than aluminum, so stainless steel is preferred over aluminum, if the insulation is adequate.
U.S. Pat. No. 4,697,327, issued Oct. 6, 1987, to Adell, shows an insulated metal door edge guard. During manufacturing, the plastic insulating material is coextruded onto a flat metal strip. The strip is then painted and roll formed to form a door edge guard.
The heat of extrusion may be used to join two materials. For example, U.S. Pat. No. 4,787,175, issued Nov. 29, 1988, to Adell, shows a non-metal door edge guard. A flat, plastic strip is extruded and the heat of extrusion is used to laminate a roll of mylar or encapsulated foil onto the plastic strip. The combination is then roll formed into a door edge guard. An adhesive may be used to improve the joining of the mylar or foil with the plastic.
In the past many door edge guards have been black or silver. More recently, though, automobile manufacturers have preferred for the door edge guards to be the same color as the automobile door. Many different methods have been used to add color to door edge guards.
As mentioned earlier, U.S. Pat. No. 4,697,327 discloses painting the plastic cover prior to roll forming, U.S. Pat. No. 4,787,175, also mentioned earlier, discloses laminating a layer of mylar onto the plastic strip.
Coextrusion has also been tried. However, when the colored material is coextruded with the plastic, the color flakes in the colored material tend to align themselves, giving the material different colors when observed from different angles.
Another method that has been attempted involves laminating colored material, such as polyvinylfluoride (PVF) onto sheets of plastic. The plastic is then cut into thin strips and roll formed.